The invention relates to a filling sleeve to be attached to a charging cone for bulk material, having an arbitrary entrance cross-section and a square or rectangular exit cross-section, for filling containers with a square or rectangular cross-section, in particular for filling clamped-on bags with side folds.
Filling sleeves of this type are used to adapt the cross-section of the filling device to the cross-section of the container, i.e. the exit cross-section of the filling device largely has to correspond to the entrance cross-section of the container which has to be filled and which, normally, is formed by a bag attached by external clamping devices to the filling sleeve. As a rule, the filling sleeves can easily be separated from the charging cone in order to be able to attach the filling sleeves which match different bag shapes and bag sizes. The entrance cross-section can be arbitrary, i.e. it can be either circular or square for example.
When filling the attached bags with material after the lock aperture in the charging cone above has been opened, the filling material preferably flows centrally into the bag which, initially, still comprises its square or rectangular shape predetermined by the exit cross-section of the filling cone. However, because the bag is filled centrally, it has a tendency to bulge out or acquire a round shape because the conically accumulating material initially applies a load to the bag wall centers. In particular, this applies to granular filling materials with bad flow properties. Such a round bagxe2x80x94after having been released by the clamping devicesxe2x80x94is difficult to close because the edges of the bag flap are no longer positioned parallel relative to one another, as was the case while the bag was being attached to the filing sleeve. Apart from the problems involved in closing the bag, bags with a round shape are disadvantageous in that they can no longer be stacked densely and securely on pallets.
It is therefore the object of the present invention to provide a filling sleeve which allows containers with a rectangular or square cross-section, especially bags originally having deep side folds, when folded flat to be filled advantageously in that they are given a stable shape. The objective is achieved by means of a filling sleeve which is characterized in that, in the exit cross-section, a central region is provided with inserts and four separate exit apertures are kept open in the corners of the square or rectangular cross-section. In this way, the filling material flowing through the substantially completely open and normally undivided entrance cross-section of the filling sleeve is divided into four individual streams which are associated with the corners of the exit cross-section. Thus, while being filled, the bags are initially stabilized from the corners, as a result of which a certain tension remains in the walls between the corners, so that the walls cannot bulge out when the level of the filling material rises. The effect is the same, both on bags clamped to the filling sleeve and on bags standing on a base. The filled bags comprise a stable rectangular or square cross-sectional shape, so that, after the bags have been filled and released from the filling sleeve, the edges of the bag flaps are positioned largely parallel relative to one another, thus allowing simple and uncomplicated closing operations. The closed bags can be stacked one above the other in a compact and secure way, and there remain very few dead spaces.
The built-in inserts in the exit cross-section of the filling sleeve have to be such that no filling material can be deposited thereon and that there is no interference in the flow of filling material due to excessive cross-sectional narrowing.
According to a first preferred embodiment, it is proposed that in the exit cross-section is a symmetrically cruciform surface provided with inserts and four identically dimensioned square or rectangular exit apertures kept free in the corners. In particular, it is proposed that two wedge elements which intersect each other in a cross-like way, are pointed towards the top and are inserted into the filling sleeve respectively centrally in the filling sleeve and so as to extend parallel to the edges of the filling sleeve. In the case of a rectangular exit cross-section one of the wedge elements may be wider and higher than the other one, whereas in the case of a square exit cross-section, identically designed wedge elements are advisable. The wedge angle in both cases can be acute, i.e. an amount to 30xc2x0 for example. In particular, the wedge angle has to be such that the wedge flanks are positioned parallel to the diverging walls of the lower portion of the filling sleeve. In this way it is possible to avoid cross-sectional narrowing which may lead to blockages in the material flow.
According to a second concrete embodiment, it is proposed that in the exit cross-section, a symmetrically arranged, cross-wise positioned square or diamond-shaped surface, be provided with inserts and four identically dimensioned triangular exit apertures are kept open in the corners of the rectangular cross-section. In particular, it is proposed that a straight pyramid with a square or rectangular base and an upwardly directed point be inserted centrally into the filling sleeve and corner-wise relative to the exit cross-section. A further addition which serves to hold the pyramid in the sleeve and to separate the material streams can consist in that between the pyramid edges and the centers of the filling sleeve walls there are inserted vertical separating plates. In particular, the latter are essential for compensating purposes if a pyramid on a square base is inserted into a rectangular exit cross-section. It is appreciated that, in consequence, in respect of the exit apertures referred to as being triangular, the triangle points positioned in the center of each filling sleeve wall are cut off by a small amount. In this embodiment, the point of the pyramid can optionally project upwardly beyond the narrowest cross-section of the filling sleeve.
In both embodiments, the filling sleeve preferably forms an upper portion with a constant cross-section or a cross-section converging from the top to the bottom thereof, and a lower portion with a constant cross-section or a cross-section which diverges from the top to the bottom thereof. In particular, the structures are built up upwardly on the exit plane of the filling sleeve. In the case of filling sleeves for small filling quantities, it is advantageous for the structures to comprise a short height above the exit plane, which height corresponds to only half the height of the lower portion. The inserts can be plate metal structures which open downwardly. In all cross-sections of the filling sleeve, the outer edge ratio does preferably not greatly differ from 1.
Two preferred embodiments of the invention are illustrated in the drawings and will be described below.